Slow File Transfer on LAN with Large Files


I’m having issues with large files transfer speeds between two SyncThing clients on a LAN. I’m hitting about 1/6th of the transfer speed I can achieve when just copying the file from a windows file share. I’ve also verified this with Iperf3 testing.

For reference, I’m peaking about 130Mbit/s, when doing the test directly I can hit 600Mbit/s (writing to an SSD stripe set). I see the drive read from the source drive peaking at 10MB/s vrs over 100MB/s when copying directly.

I’m hoping someone has a tip, but for this, but I think this might be a bug. Probably this

I suspect your bottleneck is crypto or parallelism. Check CPU usage on both sides and in advanced settings try increasing number of pullers to like 150

Every bit of data sent by Syncthing is hashed and encrypted (which includes another layer of hashing), which is quite CPU intensive. It is not comparable to a regular file share or FTP, etc.

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